This invention relates to a device which permits two components, at least one of which is a liquid, which are intended to be injected simultaneously, to be stored separately and mixed together in the same device.
Devices already available for this purpose all have one or more serious disadvantages.
In a two-chamber syringe described in German Patent Specification No. 1,791,012, the two chambers, one of which is constructed as a syringe, are connected by a slidable tube. This piece of tube slides so as to push out a seal between the chambers, whereupon the components can be mixed and drawn into the syringe. The disadvantage of this device is that construction of the connecting part is very laborious because the slidable piece of tube requires very precise finishing, especially for a vacuum-tight construction. A further disadvantage is that this device cannot be processed in an automated lyophilizing plant.
A device is described in French Patent Specification No. 1,201,070 in which a vessel is divided into two chambers by a constriction, which can be closed by a stopper. The stopper can be forced out of the constriction by piercing a closure membrane with a syringe and forcing air into one chamber, so that the two chambers are joined. This device cannot be produced or used in a lyophilization plant, which is a serious disadvantage with respect to maintaining sterile conditions during filling. Further problems are the difficulty of producing a vessel with such a precisely finished construction and fragmentation, i.e., release into the components of particles of membrane resulting from piercing the membrane. Thus, this device appears impractical for mass production.
Therefore, there is a present need for two-chamber mixing syringes which are dependable in use, simple to operate and inexpensive to produce and fill.